The present invention concerns a thin film transistor used as a switching element for a plate display.
Generally, a thin film transistor is used as a switching element for an active matrix plate display, since it realizes low driving voltage, low power consumption, light weight and high quality imaging. Such a thin film transistor will be briefly described with reference to FIG. 1.
A thin film transistor of prior art comprises a gate 2 formed on a glass substrate 1, gate insulating layers 3a and 3b formed on said gate, a semiconductor layer 4 formed on said gate insulating layers, ohmic layer 5 formed on said semiconductor layer, source and drain 6 and 7 connected to said semiconductor layer 4 with said ohmic layer 5 therebetween, and pixel electrode 8 formed on said gate insulating layer 3b contacting said drain 7.
In such a thin film transistor of prior art, there exist pin holes in the gate 2, so that the source and drain 6 and 7 are short-circuited under applied voltage. Moreover, many photolithographic etching steps are required for producing the thin film transistor, thus resulting in low yield rate. Hence, it does not properly function as a switching element for a plate display.